Arrangement for producing short waves



June 18, 1929. 0, d 1,717,656

ARRANGEMENT FOR PRODUCING SHORT WAVES Filed July 28, 1925 INVENTOR OTTO BOHM wjw ORNEY Patented June 18, 1929.

entree stares PATENT ()FFICE.

orro Bonn, or BERLIN, GERMANY, AssIeNoa TO GESELLSGHAFT Fun nRAnrLosn rnnneaarnrn M. n. n. HALLESCHES, or BERLIN, GERMANY, A conronstrron or GERMANY.

ARRANGEMENT FOR PRODUCING SHORT WAVES.

Application filed July 28, 1925, Serial No. 46,524, and in Germany August 6, 1924.

liciy invention relates n'imarily to the radio art, although my invention may be used anywhere it is desired to produce short waves of extremely constant frequency.

An object of the invention is to provide an :u'rangement in which short waves. of eX- trcmely constant frequency may be produced in a simple, cheap and el'licient manner.

Other objects will be apparent from the following description and claims which are accon'ipanicd by a drawing showing a typical wiring diagram tlior my invention.

Radio traflic and communication by the aid of very short electromagnetic waves, say, of an order of magnitude of 100 meters, has become of: increasingly greater importance. Before my invention, a by no means inconsiderable ditliculty was present in that the constancy of the frequency oi the transmitters proved inadequate. I

In order to insure proper reception by superposition, commonly known as heat or hetcrodyne reception, it is necessary that the frequency fluctuations should not be over l 100th cycle per thousand cycles, since such percentage variation results in a quite considerable difl'erencc in the tone.

Now, it is well known that in the case of spark transmitters the -treipiency is inherently extremely constant. The present invention, as will be noted, consists in using as a transmitter tor short waves a. separately con trolled tube transmitter which is controlled by a spark type t-ransmitten In this manner, the desired constancy in the frequency together with sutlicient radiation energy are realized.

To carry the idea into practice, recourse vmay be had to an arrangement in which an oscillator excited by sparks is coupled with the grid. circuit of an electron tube. The electron tube may be of any common construction, comprising an electron emitting cathode, a cold anode and a cold grid or control electrode, all sealed within an evacuated envelope. It is a convenient scheme to provide an intermediate circuit for the coupling between the oscillator and the electron tube, said intermediate circuit acting as a shock circuit, which becomes excited, and which transfers only feel ly-damped ware-trains to the grid of the tube. From the working tube the en ergy is thereupon fed to the space radiation aerial in any well-known manner.

In order to avoid back or regenerative coupling of said working tube, a thing that might quite readily happen owing to the ca pacitance between the circuits of an electron tube, and thus resulting in self-excitation of the tube, one of the well-known means adapted to compensate such undesirable coupling may be resorted to. For instance, an uncoupling device may be used, whereby the action of the grid-anode capacitance is neutralized, so that uncoupling between the anode circuit and the grid circuit is obtained.

The circuit 2, comprising the condenser 4:, inductance 6, and spark 8, is energized from an alternating current source by Way of the high frequency choke coil 12. The oscillatory circuit 2 is coupled, by means of the inductance 6, to the shock circuit 14. This in turn is coupled by means of the mutual inductance 16 to the grid circuit of the transmitter tube 18. The plate circuit is energized from the direct current source 20. The output energy is coupled to the antenna by means of the antenna inductance 24 and the I anode circuit inductance 26. The constant component of the anode potential is insulated from the output coil 26 by the condenser 28. In order to prevent self-oscillation of the vacuum tube circuits the inductance 26 is divided, and its lower half 30 is connected to the neutralizing capacitance 32. This divided. output circuit neutralizing scheme needs no detailed description, as it is already known in the art. Any other suitable oscillation prevention means may be employed.

Having described my invention I am entitled to all modifications thereof as fall fairly within the spirit and scope of my invention as defined by the following claims.

1. In combination a separately controlled transmitter, a spark oscillator for the generation of constant frequency control energy,

and means for coupling the spark oscillator,

to said separately controlled transmitter.

2. In combination, a separately cont-rolled electron discharge tube transmitter, a spark oscillator for the generation of constant frequency control energy, and means for coupling the spark oscillator to said tube transmitter.

8. In combination, a separately controlled electron discharge tube transmitter having an input circuit and an output circuit, means for neutralizing the natural coupling between spark oscillatory circuit, a source of current to energize said circuit, a vacuum tube ainplifier, means to. energize the anode circuit of said amplifier, means to prevent self-oscillation in said amplifier, and means to couple the spark circuit to the grid circuit of the vacuum tube.

DR. OTTO BGHM, 

